1. Field of the Invention
The present invention relates to an image display apparatus projecting an image with a laser beam and a position detection apparatus detecting the position of an indicator with respect to a projection image.
2. Description of the Background Art
An image display apparatus, such as a laser projector, projecting an image on a projection surface with a laser beam is put to practical use. In such an image display apparatus, a technology to detect a position in a projection image pointed by a user is known.
Japanese Patent Laying-Open No. 2009-258569 discloses an electronic device scanning a beam from an infrared laser by a part of a MEMS mirror of a projector module, rendering the beam parallel to an installation surface by a reflective mirror, and making the infrared beam reflected from a finger incident on a photodiode by a beam splitter when the finger touches a prescribed area of a projection image to measure a distance to the finger through a TOF method by distance measuring means. This electronic device detects the position of the finger in the two-dimensional surface of the projection image.
A user interface employing a projection image as a touch operation surface has been developed. This user interface is employed as a user interface of a personal computer or the like, for example, to detect an indication point, recognize that an icon in a projection image has been selected, and accomplish prescribed processing when a user indicates the icon with the finger or the like.
Although the user interface can detect the position and movement of the finger in a plane surface by detecting the indication point of the projection image in a two-dimensional surface, the user interface cannot detect an indication point in a direction perpendicular to the plane surface. In other words, the user interface cannot detect an indication point in three-dimensional space, and the number of user's operations that can be recognized is limited when the aforementioned user interface is employed.
Furthermore, a technology to project an image for a right eye and an image for a left eye to allow a user viewing these to recognize these as a three-dimensional image has been developed, for example. When this technology is employed in a user interface for a three-dimensional image, the user interface cannot detect an indication point in the height direction, so that the user interface cannot sufficiently function as a user interface.